Do Your Fowl Have Manson's Eyeworm?
Published on Tue, 12/08/2015 - 11:39am
A look at Oxyspirura mansoni
By Peter Brown, aka The Chicken Doctor
The disease known as Manson’s eyeworm, or Oxyspirura mansoni, is caused by a nematode that is a type of roundworm. These worms are quite small, and are often referred to as threadworms because of their slender appearance. These worms were first described by Dr. Patrick Manson in 1878 while he was in China. Dr. Manson, born in Scotland in 1844, worked primarily in human medicine and is referred to as "The Father of Tropical Medicine" for his groundbreaking work in the discovery of the transmission of malaria via mosquitos.
Years ago, it was uncommon to see a case of Manson’s eyeworm—it was basically a disease that was confined to more tropical regions of this and other countries. Today, with the advent of world-wide air travel and shipping, we see more and more cases of this disease each year. With most medications ineffective in treating the worms, it becomes important to understand how this is spread and how you may prevent your fowl from getting it—as well as what to do if you find that they do.
How it's spread
First, let's examine the carrier of this disease organism. The domestic chicken, turkey, peafowl, pheasant, and quail—as well as numerous free-flying birds—can all act as the definitive host for this worm. The Surinam cockroach is the intermediate host for this worm and the main method this disease is spread, or the vector.
The roach consumes feces that are contaminated with the eggs. Then, the larvae mature within the roach's body in approximately four weeks. When a chicken eats an infected roach, the larvae are released from their capsule within the roach's body, make their way up the bird's esophagus to its mouth, and then traveling through the nasolacrimal—or tear—duct, where they finally make their way to the bird's eye.
The resulting worms, while very small, are easily seen with the naked eye or with a low-power magnifying glass. Once the worms have made their way to the eye area, they lay their eggs under the nictitating membrane (the clear, transparent eyelid that isn't easy to see).
With the worms and their eggs now under the nictitating membrane, the birds will begin to scratch their eyes and rub them on their feathers in an attempt to remove the material from their eyes. Constant blinking of the infected eyes may be seen, with the cornea of the eye sometimes taking on a whitish, opaque look, similar to that seen with a bacterial eye infection.
One of the first symptoms to appear will be lacrimation of the eye, or an intense tearing. This is usually followed by conjunctivitis, the inflammation of the conjunctivae, or mucous membranes covering the white of the eye and the inner side of the eyelids. This usually provides the red color that we often see in the eye and the fluid coming from the eye may now become thickened.
This thickened material from the eye can also begin to appear on the bird’s feathers as further evidence that something is wrong. The eyes can become quite inflamed and swollen from the constant irritation and the bird’s constantly rubbing their eyes. The face-scratching and possible ocular and nasal discharge can also mimic other respiratory diseases, such as coryza.
Because of the constant tearing, the worm eggs will be washed out, traveling back down the lacrimal duct before make their way down the esophagus to be passed in the feces of the bird to begin the cycle all over again.
Controlling an infestation
The only way to get control of this situation is to eliminate the cockroach as the vector. Spray the coop and all pens with an insecticide designed to kill cockroaches. Removal of the worms from under the nictitating membrane can be accomplished by using tweezers and picking them out, one by one. They will be about three quarters of an inch to approximately one inch in length and approximately the same diameter as a piece of thread.
Placing two drops of five-percent cresol solution (if you can find it) in the birds eye will kill the worms very quickly. A few drops of a two-percent Lysol solution will kill the worms quickly as well. VetRx placed in the eye at the rate of two to three drops should work as well. Boric acid may also work to flush out the worms, but it will not kill them. Nasal flushing with a boric acid solution will help wash out worms in the nasal cavities as well.
In all above treatments, the eyes must be flushed immediately using pure water to eliminate both the contaminants and cresol, Lysol, or VetRx used to kill the worms. Birds may have to be treated several times, depending on how bad the infestation is to begin with.
All pens should be thoroughly cleaned and disinfected with a cresol-based disinfectant to make sure any worms and eggs are killed. Discard all manure since roaches are known to hide underneath, then follow up by spraying the area with both insecticide and disinfectant.
Hopefully you will not have to deal with this type of a situation on your premises, but if you do, you will at least be prepared to do battle with these insidious roaches and worms.
About the author
Peter Brown, aka The Chicken Doctor, has been caring for chickens for over 50 years and holds an AAS in poultry science. Peter is a regular on The Chicken Whisperer radio show and founder of First State Veterinary Supply.